1. Field of the Invention
This invention relates to a recording or reproducing apparatus and more particularly to a head driving control device of the recording or reproducing apparatus.
2. Description of the Related Art
The conventional recording or reproducing apparatuses include an apparatus of the kind arranged to record or reproduce information in or from a track selected from among a plurality of concentric circular tracks formed on a disc-shaped recording medium, such as a magnetic disc, by allowing a magnetic head to gain access to the tracks.
In reproducing recorded information from a track designated, the apparatus of this kind moves the magnetic head to the designated track and performs a so-called automatic tracking action to control the position of the magnetic head in such a way as to keep the head in a position where an RF signal can be reproduced from the track at a maximum level. After that, the head is controlled to continuously perform reproduction in this head position so long as no instruction is given for a change of the designated track for another.
Generally, a stepper motor is employed as a drive source for moving the magnetic head. The stepper motor is arranged to shift the position of the magnetic head toward the inner or outer circumferential side of the magnetic disc in response to a driving pulse applied.
The stepper motor is of a type called a 4-phase stepper motor having four exciting phases. As to the driving method, the stepper motor is driven by a 1-2 exciting phase change-over method. The magnetic head is moved to a desired position in accordance with the rotation of the stepper motor. The head tracking arrangement has been disclosed, for example, in U.S. Pat. Nos. No. 4,799,205 and No. 4,573,087 and U.S. patent application Ser. No. 051,479 filed on May 18, 1987.
However, in accordance with the driving method of the above-stated apparatus, the stepper motor is continuously excited by a power supply for one and the same phase even while the magnetic head is not moved, that is, even after the magnetic head is set by the automatic tracking action in a position where the RF signal can be reproduced at a maximum level. In other words, the stepper motor is continuously excited under that condition even though the power supply is effected only for one stable exciting phase. This increases the power consumption of the apparatus. In a case where a battery is used as a power source, this presents a serious problem.